1. Field of the Invention
This invention relates to a housing for tape cartridge to be used with a recording-reproducing apparatus (hereinafter called a xe2x80x9crecorderxe2x80x9d), more particularly to a housing for tape cartridge of the type having positioning walls for insertion into a recorder, and also relates to a mold for forming the housing.
2. Prior Art
For cartridges holding a reel or reels around which a length of magnetic tape is wound, recorders have positioning means to control the position of each such cartridge inserted into the machine, whereas the cartridge is formed with positioning ribs for engagement with the positioning means. For example, Japanese Patent Application Kokoku No. 63-16834 discloses a cartridge formed with low positioning ribs formed on both left and right of a tape draw-out portion at the front of the cartridge. After position control with such means, reference pins from a recorder gain entrance into reference holes formed in the underside of the cartridge to effect more precise positioning.
The prior art teaches forming positioning ribs in the tape draw-out region at the front of a cartridge, keeping them low compared with the height of side walls of the housing. Structural limitation, however, does not favor providing ribs in that location and it is preferable to form them instead on the outer surface of side wall of the housing in the direction of cartridge insertion into a recorder.
Actually molding of casings requires a draft, and the outer surface of side wall of the housing is inclined rather than perpendicular to the direction of insertion. Thus if the side wall is utilized in positioning, a problem arises in that the amount of cartridge insertion becomes instable, interrupting smooth fitting of reference pins of a recorder in the reference holes formed in the underside of the cartridge.
The problem will now be explained in more detail. FIGS. 6 and 7 illustrate the exterior side wall of an upper or lower casing of a conventional cartridge housing and a mold of the prior art for forming the casing. FIG. 6(a) shows a mold 6 closed for resin molding and FIG. 6(b), the mold opened after molding. Mold 6 is composed of a fixed mold part 61 and a movable mold part 62. It performs molding as molten resin 67 is poured into a mold cavity defined between the two mold parts 61, 62 via a gate 66 (FIG. 6(a)). After molding, the molded article is released from the mold by ascending ejector pins 64 (FIG. 6(b)).
The surface of fixed mold part 61 that makes the outer surface of side wall 26 of a casing (FIG. 7) has a draft or inclination of xcex8 (usually from 0.5 to several degrees) to the perpendicular. As a consequence, side wall 26 of a casing molded as in FIG. 7 (an enlarged view of the circled portion C in FIG. 6(b)) has an inclination 8 corresponding to the draft, and when it is partly utilized in positioning, the afore-described problem arises.
The present invention has for its object to achieve positioning of a cartridge housing with good precision by utilizing its side wall as a positioning plane.
The invention realizes the above object by a housing for tape cartridge which holds therein a tape reel on which a medium in the form of a tape is wound, characterized in that an outer surface portion of a side wall, out of surrounding walls, of the housing facing the direction of cartridge insertion into a recorder has a draft of zero degree (perpendicular to the direction of insertion) where it comes in contact with positioning means of the recorder. The invention also achieves the object by a mold for forming such a housing, characterized in that the mold portion that forms an outer surface portion of a side wall, out of surrounding walls, of the housing facing the direction of cartridge insertion into a recorder is constituted by a slide having a plane perpendicular to the direction of insertion.
With the construction described, the cartridge can be accurately positioned within a recorder since a perpendicular positioning plane formed on the wall of the cartridge housing in the direction of insertion into the recorder comes in contact with positioning means of the recorder having perpendicular contacting surface. The amount of insertion is made stable, allowing precise fitting of reference pins of the recorder into reference holes formed in the underside of the cartridge housing.